Improvement in bridges



UNITEE STATES PATENT OFFICE.

C. SHALER SMITH, C. H. LATROBE, AND FREDERICK H. SMITH, OF BALTI- MORE, MARYLAND, ASSIGNORS TO SMITH, LATROBE & CO., VOF SAME PLACE.

IMPROVEMENT IN BRIDGES.

Specification forming part of Letters Patent No. 99,017, dated January 18, 1870.

To whom it may concern.-

Be it known that we, G. SHALER SMITH, C. H. LATRoBE, and FREDERICK H. SMITH, of Baltimore, county of Baltimore and State of Maryland, have invented certain new and useful Improvements in Bridges; and we hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, in which- Figure 1 is a side elevation of a trestle-bridge made in accordance with our invention. Fig.

2 is a transverse section of the same. Figs. 3, 4,-5, and 6 are views, on an enlarged scale, of detached' parts.

Our invention may be stated to consist, rst, in the use for bridge-piers, whether the same be isolated and independent or connected so as to form a system of trestles, of wrought-iron columns or shafts with cast-iron feet, caps, or joints, substantially as hereinafter described; second, in connecting the wrought-iron columns with their cast-iron feet, caps, or joints, by fitting the wrought-iron into the casting, or the casting into the wrought-iron, or by riveting or bolting said parts together, as may be found expedient.

The Construction of the Piers.

These parts are formed of columns or shafts of wrought iron or steel, of any form of section, which, as shown in Fig. 6, fit over tenons formed on the cast-'iron foot-boxes F. These foot-boxes are bolted or otherwise suitably anchored to masonry, and to them are pinned or pivoted the straps or yokes which receive the lower ends of the longitudinal diagonal ties 4. Running through the castings, and secured thereto by bolts, are the transverse struts S3, formed each of two channel-bars, or their equivalents, for the purpose, between which the lateral ties 2 are hung. The upper end of each column ts over a tenon formed on the castiron post-cap G, Fig. 4, this cap being adapted to receive and hold-the chord-sticks, the crossstruts, the truss-chains, and the longitudinal diagonal ties. The chord-sticks are framed in pairs to the cap, one on each side of the rib that extends across its top, and on each side of which are placed the plates or bars which run through the cap and form the jaws between which the longitudinal diagonal ties take hold of the cap. These bars are heldin place by the pin upon which the truss-chains are hung, the pin passing through the hole formed for its reception in the cap, as represented in Fig. 4. The construction and arrangement of the cross-strut S1 in nowise differ from that of the strut S3 already mentioned. The lateral ties l also take hold of the cap, in the manner already described with reference to the lateral ties 2. To unite the column with its cap and foot, all that is required is to slip its ends over the tenons formed on the foot-box and cap, so that the pier can be set up with great ease and expedition. To construct the piers of considerable height, we form them in tiers or stories, and to this end we make use of cast-iron jointboxes, such as represented in Fig. 5. This joint-box, which is interposed between and forms the bearing for the contiguous ends of the sections to be united, has a tenon on each end, over which lits the upper end of the lower section, and the lower end of the upper section, to be joined in one continuous pier. As, for instance, in Fig. l, the center piers are made in three stories or tiers, AB, B C, C D, thus necessitating the employment of a footbox, cap, and two joint-boxes. The lower column C D lits over the tenon of the foot-box and the lower tenon of the first joint-box; the middle column B C lits over the upper tenon of the first and the lower tenon of the second joint-box, and so on. This method of uniting the sections combines in itself strength and ease in iitting the parts together. The contiguous ends'of the wrought-iron sections united by the joint-boxes have no contact with each other, but take a direct bearing on the boxes themselves, and the structure can be set up with great rapidity and facility. The cross- 4 strut S2, vrmade of channel-bars, is secured in the joint-box in the manner already indicated with reference to the struts S1 S2; and from between the channel-bars the lateral ties 1 2 extend in the usual manner. The two lon gitudinal tie-rods or stays 4, which meet or cross each other on the same side of the joint-box, have their straps hung upon the same pin, as shown in the figure. We stiffen the piers at their joints by means of a system of longitudinal struts, X, which are anchored or abut against masonry, or its equivalent, at each end of the bridge, and t into the joint-boxes, as seen in Eig. 5. In a continuous trestle-work we prefer, and, in fact, find it quite necessary, to make these struts, as well as the chordsticks, of wood, in order to prevent the contraction and expansion consequent upon the employment of an iron-strut system.

In illustration of our invention wehave described the method We prefer of constructing the cast-iron caps, feet, and joints, and of uniting` them with their wrought-iron columns. The construction of these parts may, however, be varied to a great extent, according as circumstances require; and so far as the method of uniting` the parts is concerned, the columns may fit over the caps, feet, and joints, or the latter may fit over the former, or the two may be riveted or bolted together, as may be found necessary in using different sections of columns. In all cases, however, we obtain piers formed of shafts or columns of wrought iron or steel, with feet, caps, and joints, where the same are employed, of cast-iron.

lVe have described so much of the structure of the bridge or piers as is necessary toillustrate the manner in which our invention is or may be carried into effect; and in conclusion we would state that we do not here claim the peculiar construction of the cast-iron caps, feet, and joint-boxes, the use of the wood chord-sticks and struts, or the use of the system of longitudinal diagonal ties, these and other features being embodied in Letters Patent recently granted to us; but

What we now claim, and desire to secure by Letters Patent, is-

l. The combination, substantially as described, of wrought-iron columns or shafts, of y. any form of section, with cast-iron caps and feetor joints, when used to form bridge-piers,A whether these piers be isolated and standing upon their own bases, or are connected by longitudinal bracing in such a Way as to form a system of wrought-iron trestle.

2. In apier composed of wrought-iron columns, combined with cast-iron caps, feet, or joint-boxes, as described, the formation'of a connection between the wrought -iron columns and their cast-iron caps, feet, or joints constitutin g the bridge-piers, by iitting the wroughtiron into the casting, or the casting into the wrought-iron, or by other means, substantially as specified, as may be found necessary in using different sections of columns, sub-5 stantially as set forth.

In testimony whereof we have signed our. names to this specificatian before two subscribing witnesses.

C. SHALER SMITH. G. H. LATROBE. FREDERICK H. SMITH.

Witnesses to U. SHALER Sm'rn:

JOHN A. KAY, Ronr. l?. ELwoR'ri-IY.

Witnesses as to O. H. LATROBE and F. H. SMITH:

M. BAILEY, A. PoLLoK. 

